POCS Camera Service

A web based camera service for use with POCS.

The service is a thin-wrapper around the gphoto2 command line utility that allows command arguments to be passed remotely via a valid JSON POST request.

Arguments

Any valid argument to gphoto2 can be given as the arguments key of a valid JSON post.

The service currently does not attempt to filter or parse the arguments, with the exception of the --filename argument.

Filenames

If the BASE_DIR envvar is set when the service starts, any --filename argument will be saved in the given directory, even if an absolute path is specified. This is designed to allow for proper saving inside a docker container where the absolute path outside the container is mapped to a different path inside the container. See Examples for more details.

Examples

Running the service

The service can be run directly via the command line or as a Docker container (see Docker above for example running in a container).

Dependencies

If running from the command line, the uvicorn web server should be installed (it is not included in the requirements file). This can be installed directly with python:

pip install uvicorn[standard]

Starting the service

The service can be started from the command line with:

uvicorn main:app --port 6565

Using the service

The service provides a single endpoint at the root of the server (i.e. /) and can be used with anything that can make valid JSON POST requests to the server.

The endpoint expects the arguments field as single string containing the arguments that would normally be passed to gphoto2.

The below examples assume the service is running at the ip 192.168.1.100 on the default port 6565.

💡 Note: The service blocks while using gphoto2, so if an exposure is 60 seconds long then there will be no response from the server during that time.

An async service is planned for the future.

From python

import requests

# Setup service info
host = '192.168.1.100'
port = 6565
endpoint = f'{host}:{port}'

# Build gphoto2 command
cmd_args = '--capture-image-and-download --filename test_image_01.cr2'

response = requests.post(endpoint, json=dict(arguments=cmd_args))
if response.ok:
    output = response.json()['output']
    print(f'Output from command: {output}')

See also the POCS example below.

From the command line

You can use HTTPie from the command line:

http 192.168.1.100:6565 arguments="--capture-image-and-download --filename test_image_01.cr2"

From POCS

If you are using POCS to control your observatory you can instantiate a remote camera:

from panoptes.pocs.camera.gphoto.remote import Camera

# Setup service info
host = '192.168.1.100'
port = 6565
endpoint = f'{host}:{port}'

# Create the camera
cam = Camera(endpoint=endpoint, name='Cam00')

# Take a picture
cam.take_exposure(seconds=2, filename='test_image_02.cr2')